Gaseous electric discharge device circuits



Oct. 14, 1952 N. o. CLARK GASEOUS ELECTRIC DISCHARGE DEVICE CIRCUITS 2SHEETSSHEET 1 Filed Nov. 8, 1950 INVENTOR 44-450 0 (24/644 ATTORN EYOct. 14, 1952 N, o. CLARK GASEOUS ELECTRIC DISCHARGE DEVICE CIRCUITS 2SHEETS-SHEET 2 Filed Nov. 8, 1950 INVENTOR m. M Q 0 N y Y E N R O T T APatented Oct. 14, 1952 GASEOUS ELECTRIC DISCHARGE DEVICE CIRCUITS Nelson0. Clark, Winthrop, Mass., assignor, by mesne assignments, to C-EightLaboratories, New Bedford, Mass, a partnership Application November 8,1950, Serial No. 194,649

3 Claims.

This invention relates generally to gaseous electric discharge devices,employing electrodes of either the hot or cold cathode types, andespecially deals with an improved system of electric circuits forsatisfactory starting and maintaining such devices in operationirrespective of whether energized by either A. C. or D. C. current, andin which circuits is employed a novel ballast arrangement in series withsuch devices.

It is well known that the operation of gaseous electric dischargedevices, commonly designated as fluorescent lamps or tubes, is basedupon emis sion of electrons between two or more electrodes r cathodes ina gaseous or vapor atmosphere confined in a closed chamber, the wall ofwhich is preferably coated internally with a fluorescent film, and whichelectronic emissions commence and continue after an initial startingperiod during which the electrodes or cathodes are subjected torelatively high heat by either the current momentarily passed throughthem, or by way of auxiliary heating means, to render them emissive,until the emission itself maintains them at a sufficient heat to assurecontinuous operation.

It is also well known that fluorescent lamps or tubes are primarilydesigned for operation with A. C. current, and that they will notoperate satisfactorily with D. 0. current without considerable changesin the wiring circuits, including the ballast.

The present invention contemplates the provision of a universal systemof electric circuits adapted to facilitate satisfactory operation ofgaseous electric discharge devices with either A. C. or D. C. currentwithout the necessity of making any changes in the circuits for suchdevices, and in which circuits is employeda combination of individualelements, such as inductances or chokes, resistances and capacitances,and which combination of elements may be designated by the general termuniversal ballast, and wherein all of the elements of such ballast inthe electric circuits of the instant universal system are always placedin series with the said gaseous electric discharge devices and, incertain embodiments of the circuits, in series with each other.

The prime object of the present invention, therefore, is the provisionof a universal system of circuits for effectively starting andmaintaining the operation of gaseous electric discharge devices at A. C.or D. C. current.

Another important object of this invention is the provision in theaforesaid system of electric circuits of a universal ballast in serieswith said devices, and wherein such ballast comprises an inductance orchoke or its equivalent, at least one resistance and at least onecapacitance, and

wherein at least one resistance or a portion of the inductance isshunted by said capacitance. Another object of this invention is thepro-via sion of a simplified, relatively inexpensively achieved and justas inexpensively maintainable electric circuit for the operation ofgaseous electric discharge devices, wherein a universal ballast isarranged in series with the latter and contains as one of its parts acondenser-shunted resistance.

Another object of this invention is the provision of a universalfluorescent lamp and ballast circuit for use with either A. C. or D. C.current, wherein is employed an inductance for providing startingvoltage, and one or more resistances in series with the inductance andin series with the lamp, and wherein either at least one of theresistances or a part of the inductance is shunted by a by-passcondenser of a relatively high capacity, said shunted resistance or saidshunted inductance serving to produce the required voltage drop for D.0. operation; said by-pass condenser serving for the reduction ofimpedance across either all or a portion of said resistance or part ofsaid inductance for A. C. operation, thereby compensating for theincreased impedance by said inductance and by the resistance orresistances for D. C. operation, the circuit thus providing for normalflow of either A. C. or D. C. current through the lamp, and whichcircuit includes either a manual or automatically operable startingdevice for, first, closing the circuit to provide an initial currentflow through the cathodes of the lamp until they are heated sufficientlyto produce emission, and, secondly, for quickly opening the circuit tosupply the required voltage surge between the cathodes to inducedischarge.

A further object of this invention is the provision of what may betermed a universal ballast forming an essential part of an electriccircuit for operating fluorescent lamps with either A. C. or D. C.current, said ballast being adapted to be placed in series with suchfluorescent lamps, and comprising a compact arrangement of an inductanceor choke coil, at least one resistance or the equivalent thereof, and acondenser shunted across a resistance.

A more specific object of this invention is the provision of a ballastconstruction composed of several elements, to wit, a choke, twoceramicencased resistances and a by-pass condenser, the latter shuntingone of the resistances, and wherein all of the elements of the ballastare placed and arranged within a metallic container adapted to dissipateheat generated by the elements when in operation.

The foregoing and numerous other important objects and additionaladvantages of the present invention will become more clearly understoodfrom the ensuing description in conjunction with the accompanyingdrawings, wherein:

Figs. 1 to 8 represent various electric circuits for gaseous electricdischarge devices employing hot cathodes;

are connected by leads I3 extending to a starting device I4, whichlatter may be operated either manually or automatically. Automaticstarting devices being well known, they are not shown.

In Fig. 1 the upper terminal of cathode II is connected to power lineI5, while from the upper terminal of cathode I2 extends lead I6 to aninductance I I, from where lead I8 passes to resistance I9, which latteris connected to another resistance 20, by-passed by condenser 2I.Resistance 20 is connected to power line 23.

In Fig. 2 the upper terminal of cathode II is again connected to a powerline lead I5, while lead I6 passes from the upper terminal of cathode I2to inductance or choke I1, from which lead 24 extends to resistance 26shunted by condenser 2|. Resistance 20 is connected to resistance I9,from which latter again extends power line 23.

A similar arrangement is shown in Fig. 3 where resistance I9 precedeschoke II, which latter is connected to resistance 20, bridged bycondenser 2 I, and from resistance 20 extends power line 23.

In Fig. 4 resistance 20, bridged by condenser 2|, precedes inductance orchoke IT, to which is connected resistance I9, from which extends powerline 23.

.From upper terminal of cathode I2 lead 24 passes to resistance 20,bridged by condenser 2|, and from resistance 20 extends lead 25 toinductance II, connected with power line 23.

In Fig. '7 power lead I passes to the upper terminal of cathode II,whereas from the upper terminal of cathode I2 lead I6 extends toinductance I'I, connected by lead 26 to resistance 20, bridged bycondenser 2I. Resistance 20 is again connected with power line 23. Itwill be noted that resistance I9, shown in Figs. 1 to 6, is omitted inthis diagram.

A modified arrangement of a universal ballast is disclosed in Fig. 8.There again power lead I5 extends to the upper terminal of cathode IIand the upper terminal of cathode I2 is connected by lead 21 to acombination inductance and resistance 28, which latter is tapped at 29.The portion of the inductance between tap 29 and the lower end 30thereof is bridged by condenser 2I and from lower end 30 extends powerline 23.

In the diagram disclosed in Fig. 9 a cold cathode tube I0 isillustrated, into which project cold cathodes II and I2. Cathode II issupplied by power line 3I from which extends a lead 32 to a startingdevice I4. The latter is connected by lead 33 over resistance 34 andlead 35 with cathode I2 and with inductance I I, from which latterextends lead 36 to resistance 20, bridged by condenser 2|, and whichresistance is connected to power line 23. It will be noted thatresistance I9 is omitted in this diagram as is the case in Fig. 7.

The arrangement of a resistance in the starting circuit, such asresistance 34 of diagram 9, may be advantageously employed in any one ofthe starting circuits disclosed in Figs. 1 to 8. In all of the diagrams1 to 9 there will be noted in the fluorescent lamps a dot 31, which isintended to indicate a drop of mercury exceeding the amount of mercuryvaporized during the operation of the lamps.

In all of the circuit diagrams illustrated in Figs. 1 to 9, it is to benoted that all the elements of the universal ballast, which comprise aninductance, and at least one resistance shunted by a condenser, arearranged in series with the fluorescent lamps. It will be further notedthat in all of the diagrams l to 4 all of the ballast elements arearranged in series with cathode I2 0f the lamps, whereas in Fig. 5 chokeI I is placed in series with cathode I I, and resistances I9 and 20 arein series with cathode I2. In the diagram of Fig. 6, on the other hand,resistance I9 is placed in series with cathode II, whereas the rest ofthe ballast elements are in series with cathode I2.

As stated above, the diagrams in Figs. 7 and 9 omit the use of anunbridged resistance in series with the lamps, and chokes II are sodesigned as to permit the elimination of such second resistance.However, the one resistance 20 bridged by condenser 2I is represented inall of the diagrams. That also applies to the diagram in Fig. 8 whereinindividual resistances are eliminated and the combination choke takestheir place.

The ballast The physical embodiment of a universal ballast arrangementas employed in connection with the various circuits illustrated is shownin detail in Figs. 10 to 12. It is preferred to construct the ballast inthe form of a single unit in which all of the ballast elements arecontained. Inasmuch as such unit is bound to become heated duringoperation, it is proposed to employ a heat-dissipating container made,for instance, from aluminum. Such container is indicated at 31 in Figs.10 and 11. It comprises a one-piece cylinder closed at its bottom 33 andprovided with a dielectric closure 39 at its open end, held in place bythe turned-over peripheral edge 40 of the cylinder. Closure 39 ispreferably made of a phenolic plastic and is provided with two aperturesM and 42 for accommodating leads 43 and 44 extending through theapertures from within the container.

Placed within container 3'! is a fibre board liner 45 which ispreferably cut out as indicated at 46 in Fig. 11, the purpose of whichcut-out will be presently explained. Inserted in the container is anelectrolytic condenser 41 extending toward the bottom 38 but nottouching the same. Arranged above the condenser is a choke coil 48 andtwo resistors 49 and 50. These resistors are spaced from choke 48 andare insulated by a suitable fibre board 5| which extends between theupper face of condenser 47 and closure 39, thus locating the condenser.

As will be seen in the diagram of Fig. 12, lead 43 extends from theupper terminal 52 of choke 48, while its lower terminal 53 is connectedby a lead 54 to the upper terminal 55 of resistance 49. From the lowerterminal of the resistance extends lead 56 to one terminal 57 ofcondenser 47, and lead 58 extends from terminal 57 to the lower terminalof resistance 50. The upper terminal 55' of resistance 59 is connectedby lead 59 to the second terminal 69 of condenser 47, and from thatterminal extends lead 44, as also seen in Figs. and 11. Thus it will beobserved, by following leads 43 and 44 in Fig. 12, that choke 48 isconnected in series with resistance 49 by lead 54, that resistance 49 isconnected through leads 56 and 58 in series with resistance 50, thelatter being shunted by condenser 47, and that terminal 69 of thecondenser forms the connecting point for leads 59 and 44.

As stated previously, lining 45 placed against the interior face ofcontainer 37 has a spareout 46. By consulting Fig. 11 it will be notedthat resistances 49 and 50, encased preferably in ceramic material, arelocated in the spareout so that the ceramic bodies of the resistancesmay directly touch casing 47, whereby heat from the resistances isdirectly transferred to the casing for dissipation. Spare-out 46 alsoserves for localizing resistances 49 and 50 within the eas- In order toprevent movement of the several elements of the ballast within thecasing it is preferred to fill all the spaces between these elements bya polyester styrene resin F, in-

troduced into the container under vacuum. When the container is thusfilled, its cover 39 is attached and the container is placed into anoven for a sufficient period of time to cure the resin until it hardensand forms a substantially rubber-like, heatand impact-resistant solid.

The arrangement of the ballast construction shown in Figs. 10, 11 and 12is useable with any one of the wiring diagrams shown in Figs. 1 to 4,however, with a few changes or modifications in the connection betweenthe ballast elements the same ballast structure can be used with thewiring arrangements illustrated in Figs. 5 to 9. Such changes beingobvious, specific ballast structures for each of the wiring diagramsshown in these figures are omitted from the drawings, it beingunderstood that, in accordance with the present invention, any ballaststructure used must contain at least one condenser-bridged resistance orits equivalent, and the elements of the ballast, including such bridgedresistance, must be placed in series with the gaseous electric dischargedevices with which they are employed in order to render such devicesoperative with either A. C. or D. C. current without resorting to theuse of auxiliary devices for effecting D. C. operation as heretoforeemployed.

As proof of the practicability of the present invention the followingdescription of a working example will be of interest. It concerns auniversal ballast for an 8 watt 117 volt standard commercial fluorescentlamp. In this ballast were employed two ceramic-encased 220 ohmresistors with a rating of 10 watts, and an electrolytic A. C. type47-58 mfd. volt condenser and a choke consisting of an inductance coilwound with size 31 nylon covered, enameled copper wire with 2,100 turnson a fibre spool, and having a resistance of approximately 55 ohms atroom temperature. The core for the coil was made of solid relay iron,held in a U-shaped yoke. The ballast with its elements connected in themanner shown in Fig. 12 was placed in series with the 8 watt lamp andproduced equally satisfactory lighting efiects with either A. C. or D.C. current.

Obviously for larger fluorescent tubes the values of the resitances aswell as of the condenser and of the choke will require modification. Bythe same token changes and rearrangements in the position of the variouselements of the ballast are contemplated for different applications, andsuch changes and modifications are deemed to reside within the broadscope of the present invention as defined in the annexed claims.

What is claimed as new is:

l. A universal ballast for electric circuits designed for operatingfluorescent lamps on A. C. or D. C. current without requiring changes inthe wiring, said ballast comprising a heat-dissipating, one-piececontainer having a dielectric, sealed closure at one end foraccommodating projecting leads, and a plurality of ballast elementsincluding a pair of ceramic-encased resistances in physical contact withthe container, an inductance and a condenser separated from each otherand from said resistances; a dielectric insulating member placed againstthe interior face of the container, but being spared out in the vicinityof the resistances, another dielectric member disposed between theinductance and said resistances, and a heatand impact-resistant,dielectric substance filling the spaces between the ballast elements.

2. In a ballast for fluorescent lamps, a heatconductive container, aninsulating member placed against the interior face thereof but having aspare-out, a plurality of ballast elements in the container including acondenser, an inductance and a pair of ceramic-encased resistances, saidresistances being disposed in the spare-out of the insulating member toeffect contact with the container, dielectric, heatand impact-resistantmeans filling the spaces between the several ballast elements within thecontainer and serving for localizing and separating said elements, saidcondenser shunting one of the resistances, said resistances and theinductance being connected in series with one another, a dielectricclosure for the container and a pair of leads extending from the endelements of the series-connected elements and projecting through theclosure.

3. In a ballast according to claim 2, said dielectric, heatandimpact-resistant space-filling means comprising a polyester styreneresin placed into the container under vacuum and heat-cured therein to arelatively hard, rubber-like solid.

NELSON O. CLARK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,020,786 Klinkhamer Nov. 12,1935 2,298,935 Freeman Oct. 13, 1942 2,327,755 Abernathy Aug. 24, 19432,461,957 Berger Feb. 15, 1949 2,472,882 Berger June 14, 1949

